Decreased Case Fatality Rate of COVID-19 in the Second Wave: a study in
53 countries.
Abstract
The raw case fatality rate (CFR, reported number of COVID-19 deaths
divided by the number of cases) is a useful indicator to quantify the
severity or treatment efficacy in a locality. In many countries, the
pandemic showed a two-wave pattern now, namely the daily reported cases
once reached a low level and now went up. To our knowledge, no study has
compared the CFR for the two waves. In this work, we report that in 53
countries or regions with the highest deaths, the CFR is reduced in 43
countries or regions in the on-going second wave. We discussed the
possible reasons. Also, we compare the two-wave pattern of COVID-19 with
the weekly influenza positive tests. The influenza activity in
pre-pandemic era provided an indicator for climate in a country, since
it is well-known that influenza is driven by weather. The sharp drop in
2020 influenza activity is an indicator of the effects of social
distancing.